A NOTE ON APPROXIMATION OF ONE-DIMENSIONAL HEAT TRANSFER WITH AND WITHOUT PHASE CHANGE

1982 ◽  
Vol 5 (2) ◽  
pp. 223-231 ◽  
Author(s):  
T. V. Hromadka II ◽  
G. L. Guymon
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
One Dimensional

Analysis of Thermal Effects in a Cavitating Orifice Using Rayleigh Equation and Experiments

2010 ◽  
Vol 132 (9) ◽  
Author(s):  
Maria Grazia De Giorgi ◽  
Daniela Bello ◽  
Antonio Ficarella
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Thermal Effects ◽  
Internal Combustion Engines ◽  
Operating Conditions ◽  
Rayleigh Equation ◽  
Liquid Temperature ◽  
Dimensional Model ◽  
Cloud Cavitation ◽  
One Dimensional

The cavitation phenomenon interests a wide range of machines, from internal combustion engines to turbines and pumps of all sizes. It affects negatively the hydraulic machines’ performance and may cause materials’ erosion. The cavitation, in most cases, is a phenomenon that develops at a constant temperature, and only a relatively small amount of heat is required for the formation of a significant volume of vapor, and the flow is assumed isothermal. However, in some cases, such as thermosensible fluids and cryogenic liquid, the heat transfer needed for the vaporization is such that phase change occurs at a temperature lower than the ambient liquid temperature. The focus of this research is the experimental and analytical studies of the cavitation phenomena in internal flows in the presence of thermal effects. Experiments have been done on water and nitrogen cavitating flows in orifices at different operating conditions. Transient growth process of the cloud cavitation induced by flow through the throat is observed using high-speed video images and analyzed by pressure signals. The experiments show different cavitating behaviors at different temperatures and different fluids; this is related to the bubble dynamics inside the flow. So to investigate possible explanations for the influence of fluid temperature and of heat transfer during the phase change, initially, a steady, quasi-one-dimensional model has been implemented to study an internal cavitating flow. The nonlinear dynamics of the bubbles has been modeled by Rayleigh–Plesset equation. In the case of nitrogen, thermal effects in the Rayleigh equation are taken into account by considering the vapor pressure at the actual bubble temperature, which is different from the liquid temperature far from the bubble. A convective approach has been used to estimate the bubble temperature. The quasisteady one-dimensional model can be extensively used to conduct parametric studies useful for fast estimation of the overall performance of any geometric design. For complex geometry, three-dimensional computational fluid dynamic (CFD) codes are necessary. In the present work good agreements have been found between numerical predictions by the CFD FLUENT code, in which a simplified form of the Rayleigh equation taking into account thermal effects has been implemented by external user routines and some experimental observations.

Perturbation Techniques in Phase Change Heat Transfer

1993 ◽  
Vol 46 (2) ◽  
pp. 29-68 ◽  
Author(s):  
A. Aziz ◽  
V. J. Lunardini
Keyword(s):  
Heat Transfer ◽  
Perturbation Theory ◽  
Phase Change ◽  
Three Dimensional ◽  
Perturbation Series ◽  
Perturbation Expansions ◽  
Regular Perturbation ◽  
One Dimensional ◽  
The Subject ◽  
Phase Change Heat Transfer

Heat transfer with change of phase (freezing or melting) is important in numerous scientific and engineering applications. Since the pioneering works of Neumann and Stefan, a number of analytical and numerical techniques have been developed to deal with freezing and melting problems. One such analytical tool is the method of perturbation expansions, which is the main focus of this work. The article begins with a review of the perturbation theory and outlines the regular perturbation method, the method of strained coordinates, the method of matched asymptotic expansions, and the recently developed method of extended perturbation series. Next, the applications of these techniques to phase change problems in Cartesian, cylindrical, and spherical systems are discussed in detail. Although the bulk of the discussion is confined to one-dimensional situations, the report also includes two- and three-dimensional cases where admittedly the success of these techniques has so far been limited. The presentation is sufficiently detailed so that even the reader who is unfamilar with the perturbation theory can understand the material without much difficulty. However, at the same time, the discussion covers the latest literature on the subject and therefore should serve as the state-of-the-art review.

scholarly journals Numerical analysis on thermal characteristics and ice melting efficiency for microwave deicing vehicle

2016 ◽  
Vol 30 (13) ◽  
pp. 1650203 ◽  
Author(s):  
Can Wang ◽  
Bo Yang ◽  
Gangfeng Tan ◽  
Xuexun Guo ◽  
Li Zhou ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Moving Boundary ◽  
Transfer Problem ◽  
Energy Generation ◽  
Heating Process ◽  
Ice Melting ◽  
Ambient Conditions ◽  
One Dimensional ◽  
Temperature Distributions

In the high latitudes, the icy patches on the road are frequently generated and have a wide distribution, which are difficult to remove and obviously affect the normal usage of the highways, bridges and airport runways. Physical deicing, such as microwave (MW) deicing, help the ice melt completely through heating mode and then the ice layer can be swept away. Though it is no pollution and no damage to the ground, the low efficiency hinders the development of MW deicing vehicle equipped without sufficient speed. In this work, the standard evaluation of deicing is put forward firstly. The intensive MW deicing is simplified to ice melting process characterized by one-dimensional slab with uniform volumetric energy generation, which results in phase transformation and interface motion between ice and water. The heating process is split into the superposition of three parts — non-heterogeneous heating for ground without phase change, heat transfer with phase change and the heat convection between top surface of ice layer and flow air. Based on the transient heat conduction theory, a mathematical model, combining electromagnetic and two-phase thermal conduction, is proposed in this work, which is able to reveal the relationship between the deicing efficiency and ambient conditions, as well as energy generation and material parameters. Using finite difference time-domain, this comprehensive model is developed to solve the moving boundary heat transfer problem in a one-dimensional structured gird. As a result, the stimulation shows the longitudinal temperature distributions in all circumstances and quantitative validation is obtained by comparing simulated temperature distributions under different conditions. In view of the best economy and fast deicing, these analytic solutions referring to the complex influence factors of deicing efficiency demonstrate the optimal matching for the new deicing design.

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